Increases valve timing accuracy by eliminating timing chain lash and the loosely fit stock cam drive sprockets. This is accomplished by replacing the stock components with light press fit S&S gear drive cams. Because the chain, chain guides and tensioner are eliminated, there is no longer a possibility for these parts to fail and damage other parts. These kits reverse the rear cam s direction of rotation and provide additional operating clearance between cam lobes, permitting the use of higher lift cams. When updating from the stock chain drive system, it is easiest to order one of these complete kits which include camshafts with inner gears, an outer cam drive gear kit, an S&S cam bearing plate, and the camshaft installation kit. S&S gear drive camshafts must be used with S&S gear drive components. Six cam profiles are available to cover a wide variety of engine displacements and compression ratios. With the exception of the bolt in 510G cam set (CC #601770), S&S gear drive cams are high lift and were designed to take advantage of the extra flow of ported stock heads or S&S Super StockTM cylinder heads. Due to the high lift of these cams, adjustable pushrods and high-performance valve springs are required for installation. If replacing cams in an engine already equipped with S&S gear drive cams, order the Gear Drive Cams with Inner Gears ONLY and reuse the existing gears. A CC #46752 camshaft installation kit is recommended. If installing a gear drive cam set without inner gears from another cam manufacturer, a CC #46760 cam gear drive kit provides the inner cam gears as well as an outer cam drive gear kit. A CC #46752 camshaft installation kit and a CC #601119 S&S cam bearing plate are also recommended. Fit all Twin Cam 88 engines from 1999 to present.